A thermoelectric conversion technology which can directly convert thermal energy into electric energy has attracted attention as one of technologies that recover and utilize waste heat which has not been used. As a means of realizing the thermoelectric conversion, a thermoelectric module has been known, which makes use of the Seebeck effect. The thermoelectric module is an assembly having pairs of thermoelectric materials made up of two types of metals or semiconductors, one type alternating with the other one. A major structure of the thermoelectric module is generally referred to as a pi type structure, in which the thermoelectric materials made up of a p-type semiconductor and n-type semiconductor are alternatingly arranged in two dimensions, and these thermoelectric materials are electrically connected in series and thermally connected in parallel via electrodes. In the thermoelectric module having the pi type structure, when there is a difference in temperature between an upper side and a lower side, carriers that carry an electric charge are diffused along thermal flux that flows from a higher temperature side to a lower temperature side, and an electric current flows in one direction if a closed circuit is made by, for example, connecting a load because the materials whose carriers have different polarities are alternatingly disposed, thereby generating the electric power.
As a manufacturing method for the thermoelectric module having the pi type structure, a method has been known, in which ingots of the thermoelectric materials are formed by a hot-press method or the like, thermoelectric conversion elements cut out from the ingots are disposed on a substrate, and electrodes are formed by soldering, metallization or the like. PTL 1 (JP2005-217055A) discloses a technique of adhering solder paste to a thermoelectric element by printing the solder paste on a circuit conductor of a substrate, arranging a plurality of n-type thermoelectric elements and p-type thermoelectric elements on a supporting member and transcribing the elements on the solder paste followed by heating.
PTL 2 (JP2010-135455A) discloses a technique that manufactures a thermoelectric conversion module by using an alloy as a raw material, the alloy comprising at least one element selected from a group of Bi and Sb and at least one element selected from a group of Te and Se. In the method manufacturing of the thermoelectric conversion module, disclosed in PTL 2, the material is once melted and formed into an ingot, the ingot is heated and melted again, and the material is cooled by a liquid quenching method and formed into powder. The resulting powder is set into a mold, heated and extruded under an atmosphere of Argon gas, and thus formed into a thermoelectric material having a necessary strength. The resulting thermoelectric material is worked to a thermoelectric module.